Melipona scutellaris (Apidae, Meliponini) is one of the main species of stingless bees used in beekeeping in the Northeast of Brazil. We examined the honey from M. scutellaris as an indicator to evaluate the levels of metals at sampling sites subject to a broad spectrum of environmental pollutants. The collections were carried out in the urban-industrial area of Salvador, Bahia and the metropolitan region. Samples (n= 58) were submitted to the nitroperchloric digestion procedure. We used the inductively coupled plasma optical emission spectrometry technique (ICP OES) to determine the concentration of metals (Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) in the samples. The studied metals were detected among the samples, which presented tolerable levels according to current Brazilian legislation and recommendations from the World Health Organization (WHO), except for Cr, which presented mean values higher than the threshold for all sampling sites. The detection of the analyzed metals indicates that the honey of M. scutellaris is a useful tool to evaluate the presence of environmental contaminants; therefore, it can be considered a good indicator of environmental contamination for monitoring a particular region and preventing issues due to the release of metals into the environment.
In the present study, a minicolumn of sisal fiber loaded with alizarin fluorine blue is proposed as a preconcentration system for copper determination in tobacco leaf samples by flame atomic absorption spectrometry. During the optimization procedure, a two level full factorial design (2(4)) was used at the preliminary evaluation of four factors, involving the following variables: sampling flow rate, elution flow rate, buffer concentration and pH. Regarding the studied levels, this design has shown that buffer concentration and pH were significant factors. The experimental conditions established in the optimization step were: pH=4.75, buffer concentration of 0.005 mol L(-1) for elution with HCl 1.0 mol L(-1) this system allows the determination of copper content with a detection limit (LD) of 0.018 μg L(-1) and a quantification limit (LQ) of 0.061 μg L(-1) precision expressed as relative standard deviation (R.S.D.) of 4.65 and 5.07%, utilizing concentration of 10 and 2.0 μg L(-1), respectively, and a preconcentration factor of 75, for a sample volume of 50.0 mL. Accuracy was confirmed by copper determination in the standard reference material, NIST SRM 1570 a trace element units in Spinach Leaves and by spike tests with recovery levels ranging from 93 to 100%; the procedure was applied for copper determination in tobacco leaf samples collected in Cruz das Almas City, Bahia, Brazil. The achieved concentrations of the three samples analyzed varied from 0.15 to 0.52 μg g(-1).
In the present work, a minicolumn of sisal fiber loaded with tiazolylazo-Resorsinol (TAR) is proposed a preconcentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. In the optimization was first of all a full factorial design of two levels (2 4 ) was used for preliminary evaluation of four factors, involving the variables: sampling flow rate, elution flow rate, buffer concentration and pH. This design has showed that, for the studied levels, buffer concentration and pH are significant factors. Using the established experimental conditions in the optimization step of: pH 7.0, buffer concentration of 0.009 mol L −1 for elution utilized HCl at 2.0 mol L −1 , this system allows the determination of cadmium with a detection limit (LD) (3σ/S) of 0.05 μg L −1 and a quantification limit (LQ) (10σ/S) of 0.17 μg L −1 , precision expressed as a relative standard deviation (R.S.D.) of 2.9 and 3.4% for a cadmium concentration of 10.0 and 20.0 μg L −1 , respectively, and a preconcentration factor of 30 for a sample volume of 50.0 mL. The accuracy was confirmed by cadmium with spike tests with recuperations varying from 92% to 103%, procedure was applied for cadmium determination in drinking water samples collected from Salvador City, Bahia, Brazil. From the five samples analyzed, the achieved concentrations varied from 0.10 to 0.54 μg L −1 .
This study evaluates the efficiency of acid extraction and total digestion to determine the presence of metals in geopropolis produced by the stingless bee Melipona scutellaris. Geopropolis samples were collected at five meliponaries in the city and in the metropolitan region of Salvador, Bahia State, Brazil. The sample treatment methods comprised acid extraction and total digestion. The Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) technique was used to quantify Cd, Cu, Cr, Pb, and Zn. Geopropolis samples submitted to both digestion methods showed statistical differences. For both methods, Cr and Zn showed the highest concentrations, while those of Cd were the lowest. The Cr concentration for determination by total digestion was 37.53 mg/kg, while for acid extraction it was 32.90 mg/kg. For Zn, the concentration was 17.65 mg/kg and 8.85 mg/kg for total digestion and acid extraction, respectively. The total digestion method showed the highest concentrations of the metals evaluated; however, acid extraction (USEPA 3050b) is a more straightforward procedure for metal evaluation in geopropolis samples and presented values that support the use of geopropolis as a bioindicator. The acid extraction method USEPA 3050b, in combination with detection using ICP OES, showed efficiency in analyses carried out to determine metals in geopropolis.
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